Ram Air Turbines (RATs) are used in aircraft to provide electric and/or hydraulic power to components of the aircraft, for example in the event of failure of other electrical or hydraulic power generating equipment on board the aircraft. In normal operation of the aircraft, the RAT is housed within the aircraft, but when needed it is extended into the airflow around the aircraft such that it may turn and generate electrical and/or hydraulic power. The RAT is typically pivoted into position by means of an actuator, for example a hydraulic actuator. The actuator typically includes a piston which extends to deploy the RAT. The actuator has a locking mechanism which prevents inadvertent movement of the piston and thus inadvertent deployment of the RAT. The locking mechanism typically comprises a spring loaded locking piston which must be moved in an axial direction to release the actuator. Such a mechanism is disclosed for example in US 2013/0327207 A1.
A release mechanism is provided to permit this movement. Typically, the release mechanism comprises a toggle type linkage, one end of which is coupled to one end of the locking piston and the other end of which is axially fixed and rotatably coupled to a support. A pair of linear solenoid actuators is coupled to the linkage and operable to move the linkage over centre between a locked and an unlocked position. The actuators are coupled to the linkage via an actuator rod which projects on both sides from the linkage. Two actuators are provided for fail safe operation.
It is desirable to mount the actuating rod in such a manner that the actuating forces on both sides of the linkage so as to provide consistent operation of the mechanism.